import math
print("{:.3}".format(math.pi))
print("<---常用运算符--->")
x=10
y=20
print("X={}  Y={}".format(x,y))
print("+ = {}\n- = {}\n* = {}\n/ = {}\n** = {}\n// = {}".format(x+y,x-y,x*y,x/y,x**2,x//y))
print("<---常用运算符优先级-**>//>*>/>+>-..-->\n")
print("{}\n{}\n{}".format(30-3**2+8//3**2**10,3*4**2/8%5,2**2**3))
print("<-----表达式结果----->")
x=(2**4+7-3*4)/5
y=(1+pow(3,2))*(16%7)/7
print("X = {} Y = {:.3}".format(x,y))
